blob: 61fdaf02f2511fb09aa6008ab5d78b354d39554b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
3 *
4 * SCSI queueing library.
5 * Initial versions: Eric Youngdale (eric@andante.org).
6 * Based upon conversations with large numbers
7 * of people at Linux Expo.
8 */
9
10#include <linux/bio.h>
11#include <linux/blkdev.h>
12#include <linux/completion.h>
13#include <linux/kernel.h>
14#include <linux/mempool.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17#include <linux/pci.h>
18#include <linux/delay.h>
James Bottomleyfaead262006-02-14 10:42:07 -060019#include <linux/hardirq.h>
Jens Axboec6132da2007-10-16 11:08:49 +020020#include <linux/scatterlist.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
22#include <scsi/scsi.h>
Christoph Hellwigbeb40482006-06-10 18:01:03 +020023#include <scsi/scsi_cmnd.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <scsi/scsi_dbg.h>
25#include <scsi/scsi_device.h>
26#include <scsi/scsi_driver.h>
27#include <scsi/scsi_eh.h>
28#include <scsi/scsi_host.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
30#include "scsi_priv.h"
31#include "scsi_logging.h"
32
33
Tobias Klauser6391a112006-06-08 22:23:48 -070034#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
Jens Axboe59725112007-04-02 10:06:42 +020035#define SG_MEMPOOL_SIZE 2
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
FUJITA Tomonorifd820f42007-09-18 12:14:37 +020037/*
38 * The maximum number of SG segments that we will put inside a scatterlist
39 * (unless chaining is used). Should ideally fit inside a single page, to
40 * avoid a higher order allocation.
41 */
42#define SCSI_MAX_SG_SEGMENTS 128
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044struct scsi_host_sg_pool {
45 size_t size;
Jens Axboea8474ce2007-08-07 09:02:51 +020046 char *name;
Christoph Lametere18b8902006-12-06 20:33:20 -080047 struct kmem_cache *slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 mempool_t *pool;
49};
50
Jens Axboea8474ce2007-08-07 09:02:51 +020051#define SP(x) { x, "sgpool-" #x }
Adrian Bunk52c1da32005-06-23 22:05:33 -070052static struct scsi_host_sg_pool scsi_sg_pools[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 SP(8),
54 SP(16),
FUJITA Tomonorifd820f42007-09-18 12:14:37 +020055#if (SCSI_MAX_SG_SEGMENTS > 16)
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 SP(32),
FUJITA Tomonorifd820f42007-09-18 12:14:37 +020057#if (SCSI_MAX_SG_SEGMENTS > 32)
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 SP(64),
FUJITA Tomonorifd820f42007-09-18 12:14:37 +020059#if (SCSI_MAX_SG_SEGMENTS > 64)
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 SP(128),
FUJITA Tomonorifd820f42007-09-18 12:14:37 +020061#endif
62#endif
63#endif
Jens Axboea8474ce2007-08-07 09:02:51 +020064};
Linus Torvalds1da177e2005-04-16 15:20:36 -070065#undef SP
66
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -050067static void scsi_run_queue(struct request_queue *q);
James Bottomleye91442b2005-09-09 10:44:16 -050068
69/*
70 * Function: scsi_unprep_request()
71 *
72 * Purpose: Remove all preparation done for a request, including its
73 * associated scsi_cmnd, so that it can be requeued.
74 *
75 * Arguments: req - request to unprepare
76 *
77 * Lock status: Assumed that no locks are held upon entry.
78 *
79 * Returns: Nothing.
80 */
81static void scsi_unprep_request(struct request *req)
82{
83 struct scsi_cmnd *cmd = req->special;
84
Jens Axboe4aff5e22006-08-10 08:44:47 +020085 req->cmd_flags &= ~REQ_DONTPREP;
Christoph Hellwigbeb40482006-06-10 18:01:03 +020086 req->special = NULL;
James Bottomleye91442b2005-09-09 10:44:16 -050087
James Bottomleye91442b2005-09-09 10:44:16 -050088 scsi_put_command(cmd);
89}
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -050090
Linus Torvalds1da177e2005-04-16 15:20:36 -070091/*
92 * Function: scsi_queue_insert()
93 *
94 * Purpose: Insert a command in the midlevel queue.
95 *
96 * Arguments: cmd - command that we are adding to queue.
97 * reason - why we are inserting command to queue.
98 *
99 * Lock status: Assumed that lock is not held upon entry.
100 *
101 * Returns: Nothing.
102 *
103 * Notes: We do this for one of two cases. Either the host is busy
104 * and it cannot accept any more commands for the time being,
105 * or the device returned QUEUE_FULL and can accept no more
106 * commands.
107 * Notes: This could be called either from an interrupt context or a
108 * normal process context.
109 */
110int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
111{
112 struct Scsi_Host *host = cmd->device->host;
113 struct scsi_device *device = cmd->device;
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500114 struct request_queue *q = device->request_queue;
115 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
117 SCSI_LOG_MLQUEUE(1,
118 printk("Inserting command %p into mlqueue\n", cmd));
119
120 /*
Tejun Heo d8c37e72005-05-14 00:46:08 +0900121 * Set the appropriate busy bit for the device/host.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 *
123 * If the host/device isn't busy, assume that something actually
124 * completed, and that we should be able to queue a command now.
125 *
126 * Note that the prior mid-layer assumption that any host could
127 * always queue at least one command is now broken. The mid-layer
128 * will implement a user specifiable stall (see
129 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
130 * if a command is requeued with no other commands outstanding
131 * either for the device or for the host.
132 */
133 if (reason == SCSI_MLQUEUE_HOST_BUSY)
134 host->host_blocked = host->max_host_blocked;
135 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
136 device->device_blocked = device->max_device_blocked;
137
138 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 * Decrement the counters, since these commands are no longer
140 * active on the host/device.
141 */
142 scsi_device_unbusy(device);
143
144 /*
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500145 * Requeue this command. It will go before all other commands
146 * that are already in the queue.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 *
148 * NOTE: there is magic here about the way the queue is plugged if
149 * we have no outstanding commands.
150 *
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500151 * Although we *don't* plug the queue, we call the request
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 * function. The SCSI request function detects the blocked condition
153 * and plugs the queue appropriately.
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500154 */
155 spin_lock_irqsave(q->queue_lock, flags);
James Bottomley59897da2005-09-14 12:57:42 -0400156 blk_requeue_request(q, cmd->request);
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500157 spin_unlock_irqrestore(q->queue_lock, flags);
158
159 scsi_run_queue(q);
160
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 return 0;
162}
163
James Bottomley39216032005-06-15 18:48:29 -0500164/**
James Bottomley33aa6872005-08-28 11:31:14 -0500165 * scsi_execute - insert request and wait for the result
James Bottomley39216032005-06-15 18:48:29 -0500166 * @sdev: scsi device
167 * @cmd: scsi command
168 * @data_direction: data direction
169 * @buffer: data buffer
170 * @bufflen: len of buffer
171 * @sense: optional sense buffer
172 * @timeout: request timeout in seconds
173 * @retries: number of times to retry request
James Bottomley33aa6872005-08-28 11:31:14 -0500174 * @flags: or into request flags;
James Bottomley39216032005-06-15 18:48:29 -0500175 *
Michael Opdenacker59c51592007-05-09 08:57:56 +0200176 * returns the req->errors value which is the scsi_cmnd result
James Bottomleyea73a9f2005-08-28 11:33:52 -0500177 * field.
James Bottomley39216032005-06-15 18:48:29 -0500178 **/
James Bottomley33aa6872005-08-28 11:31:14 -0500179int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
180 int data_direction, void *buffer, unsigned bufflen,
181 unsigned char *sense, int timeout, int retries, int flags)
James Bottomley39216032005-06-15 18:48:29 -0500182{
183 struct request *req;
184 int write = (data_direction == DMA_TO_DEVICE);
185 int ret = DRIVER_ERROR << 24;
186
187 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
188
189 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
190 buffer, bufflen, __GFP_WAIT))
191 goto out;
192
193 req->cmd_len = COMMAND_SIZE(cmd[0]);
194 memcpy(req->cmd, cmd, req->cmd_len);
195 req->sense = sense;
196 req->sense_len = 0;
Mike Christie17e01f22005-11-11 05:31:37 -0600197 req->retries = retries;
James Bottomley39216032005-06-15 18:48:29 -0500198 req->timeout = timeout;
Jens Axboe4aff5e22006-08-10 08:44:47 +0200199 req->cmd_type = REQ_TYPE_BLOCK_PC;
200 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
James Bottomley39216032005-06-15 18:48:29 -0500201
202 /*
203 * head injection *required* here otherwise quiesce won't work
204 */
205 blk_execute_rq(req->q, NULL, req, 1);
206
207 ret = req->errors;
208 out:
209 blk_put_request(req);
210
211 return ret;
212}
James Bottomley33aa6872005-08-28 11:31:14 -0500213EXPORT_SYMBOL(scsi_execute);
James Bottomley39216032005-06-15 18:48:29 -0500214
James Bottomleyea73a9f2005-08-28 11:33:52 -0500215
216int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
217 int data_direction, void *buffer, unsigned bufflen,
218 struct scsi_sense_hdr *sshdr, int timeout, int retries)
219{
220 char *sense = NULL;
akpm@osdl.org1ccb48b2005-06-26 00:12:51 -0700221 int result;
222
James Bottomleyea73a9f2005-08-28 11:33:52 -0500223 if (sshdr) {
Jes Sorensen24669f752006-01-16 10:31:18 -0500224 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
James Bottomleyea73a9f2005-08-28 11:33:52 -0500225 if (!sense)
226 return DRIVER_ERROR << 24;
James Bottomleyea73a9f2005-08-28 11:33:52 -0500227 }
akpm@osdl.org1ccb48b2005-06-26 00:12:51 -0700228 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
Jes Sorensen24669f752006-01-16 10:31:18 -0500229 sense, timeout, retries, 0);
James Bottomleyea73a9f2005-08-28 11:33:52 -0500230 if (sshdr)
James Bottomleye5143852005-08-09 11:55:36 -0500231 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
James Bottomleyea73a9f2005-08-28 11:33:52 -0500232
233 kfree(sense);
234 return result;
235}
236EXPORT_SYMBOL(scsi_execute_req);
237
Mike Christie6e68af62005-11-11 05:30:27 -0600238struct scsi_io_context {
239 void *data;
240 void (*done)(void *data, char *sense, int result, int resid);
241 char sense[SCSI_SENSE_BUFFERSIZE];
242};
243
Christoph Lametere18b8902006-12-06 20:33:20 -0800244static struct kmem_cache *scsi_io_context_cache;
Mike Christieaa7b5cd2005-11-11 05:31:41 -0600245
Jens Axboee650c302006-01-06 12:38:30 +0100246static void scsi_end_async(struct request *req, int uptodate)
Mike Christie6e68af62005-11-11 05:30:27 -0600247{
248 struct scsi_io_context *sioc = req->end_io_data;
249
250 if (sioc->done)
251 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
252
Mike Christieaa7b5cd2005-11-11 05:31:41 -0600253 kmem_cache_free(scsi_io_context_cache, sioc);
Mike Christie6e68af62005-11-11 05:30:27 -0600254 __blk_put_request(req->q, req);
255}
256
257static int scsi_merge_bio(struct request *rq, struct bio *bio)
258{
259 struct request_queue *q = rq->q;
260
261 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
262 if (rq_data_dir(rq) == WRITE)
263 bio->bi_rw |= (1 << BIO_RW);
264 blk_queue_bounce(q, &bio);
265
NeilBrown3001ca72007-08-16 13:31:27 +0200266 return blk_rq_append_bio(q, rq, bio);
Mike Christie6e68af62005-11-11 05:30:27 -0600267}
268
NeilBrown6712ecf2007-09-27 12:47:43 +0200269static void scsi_bi_endio(struct bio *bio, int error)
Mike Christie6e68af62005-11-11 05:30:27 -0600270{
Mike Christie6e68af62005-11-11 05:30:27 -0600271 bio_put(bio);
Mike Christie6e68af62005-11-11 05:30:27 -0600272}
273
274/**
275 * scsi_req_map_sg - map a scatterlist into a request
276 * @rq: request to fill
277 * @sg: scatterlist
278 * @nsegs: number of elements
279 * @bufflen: len of buffer
280 * @gfp: memory allocation flags
281 *
282 * scsi_req_map_sg maps a scatterlist into a request so that the
283 * request can be sent to the block layer. We do not trust the scatterlist
284 * sent to use, as some ULDs use that struct to only organize the pages.
285 */
286static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
287 int nsegs, unsigned bufflen, gfp_t gfp)
288{
289 struct request_queue *q = rq->q;
Bryan Holtyf5235962006-03-22 06:35:39 -0600290 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
Mike Christiebd441de2007-03-13 12:52:29 -0500291 unsigned int data_len = bufflen, len, bytes, off;
Jens Axboec6132da2007-10-16 11:08:49 +0200292 struct scatterlist *sg;
Mike Christie6e68af62005-11-11 05:30:27 -0600293 struct page *page;
294 struct bio *bio = NULL;
295 int i, err, nr_vecs = 0;
296
Jens Axboec6132da2007-10-16 11:08:49 +0200297 for_each_sg(sgl, sg, nsegs, i) {
Jens Axboe45711f12007-10-22 21:19:53 +0200298 page = sg_page(sg);
Jens Axboec6132da2007-10-16 11:08:49 +0200299 off = sg->offset;
300 len = sg->length;
301 data_len += len;
Mike Christie6e68af62005-11-11 05:30:27 -0600302
Mike Christiebd441de2007-03-13 12:52:29 -0500303 while (len > 0 && data_len > 0) {
304 /*
305 * sg sends a scatterlist that is larger than
306 * the data_len it wants transferred for certain
307 * IO sizes
308 */
Mike Christie6e68af62005-11-11 05:30:27 -0600309 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
Mike Christiebd441de2007-03-13 12:52:29 -0500310 bytes = min(bytes, data_len);
Mike Christie6e68af62005-11-11 05:30:27 -0600311
312 if (!bio) {
313 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
314 nr_pages -= nr_vecs;
315
316 bio = bio_alloc(gfp, nr_vecs);
317 if (!bio) {
318 err = -ENOMEM;
319 goto free_bios;
320 }
321 bio->bi_end_io = scsi_bi_endio;
322 }
323
324 if (bio_add_pc_page(q, bio, page, bytes, off) !=
325 bytes) {
326 bio_put(bio);
327 err = -EINVAL;
328 goto free_bios;
329 }
330
331 if (bio->bi_vcnt >= nr_vecs) {
332 err = scsi_merge_bio(rq, bio);
333 if (err) {
NeilBrown6712ecf2007-09-27 12:47:43 +0200334 bio_endio(bio, 0);
Mike Christie6e68af62005-11-11 05:30:27 -0600335 goto free_bios;
336 }
337 bio = NULL;
338 }
339
340 page++;
341 len -= bytes;
Mike Christiebd441de2007-03-13 12:52:29 -0500342 data_len -=bytes;
Mike Christie6e68af62005-11-11 05:30:27 -0600343 off = 0;
344 }
345 }
346
347 rq->buffer = rq->data = NULL;
Mike Christiebd441de2007-03-13 12:52:29 -0500348 rq->data_len = bufflen;
Mike Christie6e68af62005-11-11 05:30:27 -0600349 return 0;
350
351free_bios:
352 while ((bio = rq->bio) != NULL) {
353 rq->bio = bio->bi_next;
354 /*
355 * call endio instead of bio_put incase it was bounced
356 */
NeilBrown6712ecf2007-09-27 12:47:43 +0200357 bio_endio(bio, 0);
Mike Christie6e68af62005-11-11 05:30:27 -0600358 }
359
360 return err;
361}
362
363/**
364 * scsi_execute_async - insert request
365 * @sdev: scsi device
366 * @cmd: scsi command
brking@us.ibm.combb1d1072006-01-23 15:03:22 -0600367 * @cmd_len: length of scsi cdb
Mike Christie6e68af62005-11-11 05:30:27 -0600368 * @data_direction: data direction
369 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
370 * @bufflen: len of buffer
371 * @use_sg: if buffer is a scatterlist this is the number of elements
372 * @timeout: request timeout in seconds
373 * @retries: number of times to retry request
374 * @flags: or into request flags
375 **/
376int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
brking@us.ibm.combb1d1072006-01-23 15:03:22 -0600377 int cmd_len, int data_direction, void *buffer, unsigned bufflen,
Mike Christie6e68af62005-11-11 05:30:27 -0600378 int use_sg, int timeout, int retries, void *privdata,
379 void (*done)(void *, char *, int, int), gfp_t gfp)
380{
381 struct request *req;
382 struct scsi_io_context *sioc;
383 int err = 0;
384 int write = (data_direction == DMA_TO_DEVICE);
385
Robert P. J. Dayc3762222007-02-10 01:45:03 -0800386 sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp);
Mike Christie6e68af62005-11-11 05:30:27 -0600387 if (!sioc)
388 return DRIVER_ERROR << 24;
389
390 req = blk_get_request(sdev->request_queue, write, gfp);
391 if (!req)
392 goto free_sense;
Jens Axboe4aff5e22006-08-10 08:44:47 +0200393 req->cmd_type = REQ_TYPE_BLOCK_PC;
394 req->cmd_flags |= REQ_QUIET;
Mike Christie6e68af62005-11-11 05:30:27 -0600395
396 if (use_sg)
397 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
398 else if (bufflen)
399 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
400
401 if (err)
402 goto free_req;
403
brking@us.ibm.combb1d1072006-01-23 15:03:22 -0600404 req->cmd_len = cmd_len;
Tejun Heo097b8452006-11-16 01:19:31 -0800405 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
Mike Christie6e68af62005-11-11 05:30:27 -0600406 memcpy(req->cmd, cmd, req->cmd_len);
407 req->sense = sioc->sense;
408 req->sense_len = 0;
409 req->timeout = timeout;
Mike Christie17e01f22005-11-11 05:31:37 -0600410 req->retries = retries;
Mike Christie6e68af62005-11-11 05:30:27 -0600411 req->end_io_data = sioc;
412
413 sioc->data = privdata;
414 sioc->done = done;
415
416 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
417 return 0;
418
419free_req:
420 blk_put_request(req);
421free_sense:
Arne Redlich6470f2b2006-09-30 15:49:40 +0200422 kmem_cache_free(scsi_io_context_cache, sioc);
Mike Christie6e68af62005-11-11 05:30:27 -0600423 return DRIVER_ERROR << 24;
424}
425EXPORT_SYMBOL_GPL(scsi_execute_async);
426
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427/*
428 * Function: scsi_init_cmd_errh()
429 *
430 * Purpose: Initialize cmd fields related to error handling.
431 *
432 * Arguments: cmd - command that is ready to be queued.
433 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 * Notes: This function has the job of initializing a number of
435 * fields related to error handling. Typically this will
436 * be called once for each command, as required.
437 */
Christoph Hellwig631c2282006-07-08 20:42:15 +0200438static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 cmd->serial_number = 0;
Michael Reed52aeeca2007-09-17 15:11:39 -0700441 cmd->resid = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 if (cmd->cmd_len == 0)
444 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445}
446
447void scsi_device_unbusy(struct scsi_device *sdev)
448{
449 struct Scsi_Host *shost = sdev->host;
450 unsigned long flags;
451
452 spin_lock_irqsave(shost->host_lock, flags);
453 shost->host_busy--;
James Bottomley939647e2005-09-18 15:05:20 -0500454 if (unlikely(scsi_host_in_recovery(shost) &&
Tejun Heoee7863b2006-05-15 20:57:20 +0900455 (shost->host_failed || shost->host_eh_scheduled)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 scsi_eh_wakeup(shost);
457 spin_unlock(shost->host_lock);
152587d2005-04-12 16:22:06 -0500458 spin_lock(sdev->request_queue->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 sdev->device_busy--;
152587d2005-04-12 16:22:06 -0500460 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461}
462
463/*
464 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
465 * and call blk_run_queue for all the scsi_devices on the target -
466 * including current_sdev first.
467 *
468 * Called with *no* scsi locks held.
469 */
470static void scsi_single_lun_run(struct scsi_device *current_sdev)
471{
472 struct Scsi_Host *shost = current_sdev->host;
473 struct scsi_device *sdev, *tmp;
474 struct scsi_target *starget = scsi_target(current_sdev);
475 unsigned long flags;
476
477 spin_lock_irqsave(shost->host_lock, flags);
478 starget->starget_sdev_user = NULL;
479 spin_unlock_irqrestore(shost->host_lock, flags);
480
481 /*
482 * Call blk_run_queue for all LUNs on the target, starting with
483 * current_sdev. We race with others (to set starget_sdev_user),
484 * but in most cases, we will be first. Ideally, each LU on the
485 * target would get some limited time or requests on the target.
486 */
487 blk_run_queue(current_sdev->request_queue);
488
489 spin_lock_irqsave(shost->host_lock, flags);
490 if (starget->starget_sdev_user)
491 goto out;
492 list_for_each_entry_safe(sdev, tmp, &starget->devices,
493 same_target_siblings) {
494 if (sdev == current_sdev)
495 continue;
496 if (scsi_device_get(sdev))
497 continue;
498
499 spin_unlock_irqrestore(shost->host_lock, flags);
500 blk_run_queue(sdev->request_queue);
501 spin_lock_irqsave(shost->host_lock, flags);
502
503 scsi_device_put(sdev);
504 }
505 out:
506 spin_unlock_irqrestore(shost->host_lock, flags);
507}
508
509/*
510 * Function: scsi_run_queue()
511 *
512 * Purpose: Select a proper request queue to serve next
513 *
514 * Arguments: q - last request's queue
515 *
516 * Returns: Nothing
517 *
518 * Notes: The previous command was completely finished, start
519 * a new one if possible.
520 */
521static void scsi_run_queue(struct request_queue *q)
522{
523 struct scsi_device *sdev = q->queuedata;
524 struct Scsi_Host *shost = sdev->host;
525 unsigned long flags;
526
527 if (sdev->single_lun)
528 scsi_single_lun_run(sdev);
529
530 spin_lock_irqsave(shost->host_lock, flags);
531 while (!list_empty(&shost->starved_list) &&
532 !shost->host_blocked && !shost->host_self_blocked &&
533 !((shost->can_queue > 0) &&
534 (shost->host_busy >= shost->can_queue))) {
535 /*
536 * As long as shost is accepting commands and we have
537 * starved queues, call blk_run_queue. scsi_request_fn
538 * drops the queue_lock and can add us back to the
539 * starved_list.
540 *
541 * host_lock protects the starved_list and starved_entry.
542 * scsi_request_fn must get the host_lock before checking
543 * or modifying starved_list or starved_entry.
544 */
545 sdev = list_entry(shost->starved_list.next,
546 struct scsi_device, starved_entry);
547 list_del_init(&sdev->starved_entry);
548 spin_unlock_irqrestore(shost->host_lock, flags);
549
Andreas Herrmann04846f22006-08-09 17:31:16 +0200550
551 if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
552 !test_and_set_bit(QUEUE_FLAG_REENTER,
553 &sdev->request_queue->queue_flags)) {
554 blk_run_queue(sdev->request_queue);
555 clear_bit(QUEUE_FLAG_REENTER,
556 &sdev->request_queue->queue_flags);
557 } else
558 blk_run_queue(sdev->request_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559
560 spin_lock_irqsave(shost->host_lock, flags);
561 if (unlikely(!list_empty(&sdev->starved_entry)))
562 /*
563 * sdev lost a race, and was put back on the
564 * starved list. This is unlikely but without this
565 * in theory we could loop forever.
566 */
567 break;
568 }
569 spin_unlock_irqrestore(shost->host_lock, flags);
570
571 blk_run_queue(q);
572}
573
574/*
575 * Function: scsi_requeue_command()
576 *
577 * Purpose: Handle post-processing of completed commands.
578 *
579 * Arguments: q - queue to operate on
580 * cmd - command that may need to be requeued.
581 *
582 * Returns: Nothing
583 *
584 * Notes: After command completion, there may be blocks left
585 * over which weren't finished by the previous command
586 * this can be for a number of reasons - the main one is
587 * I/O errors in the middle of the request, in which case
588 * we need to request the blocks that come after the bad
589 * sector.
James Bottomleye91442b2005-09-09 10:44:16 -0500590 * Notes: Upon return, cmd is a stale pointer.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 */
592static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
593{
James Bottomleye91442b2005-09-09 10:44:16 -0500594 struct request *req = cmd->request;
Tejun Heo 283369c2005-04-24 02:06:36 -0500595 unsigned long flags;
596
James Bottomleye91442b2005-09-09 10:44:16 -0500597 scsi_unprep_request(req);
Tejun Heo 283369c2005-04-24 02:06:36 -0500598 spin_lock_irqsave(q->queue_lock, flags);
James Bottomleye91442b2005-09-09 10:44:16 -0500599 blk_requeue_request(q, req);
Tejun Heo 283369c2005-04-24 02:06:36 -0500600 spin_unlock_irqrestore(q->queue_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601
602 scsi_run_queue(q);
603}
604
605void scsi_next_command(struct scsi_cmnd *cmd)
606{
Linus Torvalds49d7bc62005-12-12 11:25:04 -0800607 struct scsi_device *sdev = cmd->device;
608 struct request_queue *q = sdev->request_queue;
609
610 /* need to hold a reference on the device before we let go of the cmd */
611 get_device(&sdev->sdev_gendev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612
613 scsi_put_command(cmd);
614 scsi_run_queue(q);
Linus Torvalds49d7bc62005-12-12 11:25:04 -0800615
616 /* ok to remove device now */
617 put_device(&sdev->sdev_gendev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618}
619
620void scsi_run_host_queues(struct Scsi_Host *shost)
621{
622 struct scsi_device *sdev;
623
624 shost_for_each_device(sdev, shost)
625 scsi_run_queue(sdev->request_queue);
626}
627
628/*
629 * Function: scsi_end_request()
630 *
631 * Purpose: Post-processing of completed commands (usually invoked at end
632 * of upper level post-processing and scsi_io_completion).
633 *
634 * Arguments: cmd - command that is complete.
635 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
636 * bytes - number of bytes of completed I/O
637 * requeue - indicates whether we should requeue leftovers.
638 *
639 * Lock status: Assumed that lock is not held upon entry.
640 *
James Bottomleye91442b2005-09-09 10:44:16 -0500641 * Returns: cmd if requeue required, NULL otherwise.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 *
643 * Notes: This is called for block device requests in order to
644 * mark some number of sectors as complete.
645 *
646 * We are guaranteeing that the request queue will be goosed
647 * at some point during this call.
James Bottomleye91442b2005-09-09 10:44:16 -0500648 * Notes: If cmd was requeued, upon return it will be a stale pointer.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649 */
650static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
651 int bytes, int requeue)
652{
Jens Axboe165125e2007-07-24 09:28:11 +0200653 struct request_queue *q = cmd->device->request_queue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654 struct request *req = cmd->request;
655 unsigned long flags;
656
657 /*
658 * If there are blocks left over at the end, set up the command
659 * to queue the remainder of them.
660 */
661 if (end_that_request_chunk(req, uptodate, bytes)) {
662 int leftover = (req->hard_nr_sectors << 9);
663
664 if (blk_pc_request(req))
665 leftover = req->data_len;
666
667 /* kill remainder if no retrys */
668 if (!uptodate && blk_noretry_request(req))
669 end_that_request_chunk(req, 0, leftover);
670 else {
James Bottomleye91442b2005-09-09 10:44:16 -0500671 if (requeue) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 /*
673 * Bleah. Leftovers again. Stick the
674 * leftovers in the front of the
675 * queue, and goose the queue again.
676 */
677 scsi_requeue_command(q, cmd);
James Bottomleye91442b2005-09-09 10:44:16 -0500678 cmd = NULL;
679 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 return cmd;
681 }
682 }
683
684 add_disk_randomness(req->rq_disk);
685
686 spin_lock_irqsave(q->queue_lock, flags);
687 if (blk_rq_tagged(req))
688 blk_queue_end_tag(q, req);
Tejun Heo8ffdc652006-01-06 09:49:03 +0100689 end_that_request_last(req, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 spin_unlock_irqrestore(q->queue_lock, flags);
691
692 /*
693 * This will goose the queue request function at the end, so we don't
694 * need to worry about launching another command.
695 */
696 scsi_next_command(cmd);
697 return NULL;
698}
699
Jens Axboea8474ce2007-08-07 09:02:51 +0200700/*
Jens Axboea8474ce2007-08-07 09:02:51 +0200701 * Like SCSI_MAX_SG_SEGMENTS, but for archs that have sg chaining. This limit
702 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
703 */
704#define SCSI_MAX_SG_CHAIN_SEGMENTS 2048
705
706static inline unsigned int scsi_sgtable_index(unsigned short nents)
707{
708 unsigned int index;
709
710 switch (nents) {
711 case 1 ... 8:
712 index = 0;
713 break;
714 case 9 ... 16:
715 index = 1;
716 break;
FUJITA Tomonorifd820f42007-09-18 12:14:37 +0200717#if (SCSI_MAX_SG_SEGMENTS > 16)
Jens Axboea8474ce2007-08-07 09:02:51 +0200718 case 17 ... 32:
719 index = 2;
720 break;
FUJITA Tomonorifd820f42007-09-18 12:14:37 +0200721#if (SCSI_MAX_SG_SEGMENTS > 32)
Jens Axboea8474ce2007-08-07 09:02:51 +0200722 case 33 ... 64:
723 index = 3;
724 break;
FUJITA Tomonorifd820f42007-09-18 12:14:37 +0200725#if (SCSI_MAX_SG_SEGMENTS > 64)
726 case 65 ... 128:
Jens Axboea8474ce2007-08-07 09:02:51 +0200727 index = 4;
728 break;
FUJITA Tomonorifd820f42007-09-18 12:14:37 +0200729#endif
730#endif
731#endif
Jens Axboea8474ce2007-08-07 09:02:51 +0200732 default:
733 printk(KERN_ERR "scsi: bad segment count=%d\n", nents);
734 BUG();
735 }
736
737 return index;
738}
739
FUJITA Tomonorib58d9152006-11-16 19:24:10 +0900740struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741{
742 struct scsi_host_sg_pool *sgp;
Jens Axboea8474ce2007-08-07 09:02:51 +0200743 struct scatterlist *sgl, *prev, *ret;
744 unsigned int index;
745 int this, left;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746
747 BUG_ON(!cmd->use_sg);
748
Jens Axboea8474ce2007-08-07 09:02:51 +0200749 left = cmd->use_sg;
750 ret = prev = NULL;
751 do {
752 this = left;
753 if (this > SCSI_MAX_SG_SEGMENTS) {
754 this = SCSI_MAX_SG_SEGMENTS - 1;
755 index = SG_MEMPOOL_NR - 1;
756 } else
757 index = scsi_sgtable_index(this);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758
Jens Axboea8474ce2007-08-07 09:02:51 +0200759 left -= this;
760
761 sgp = scsi_sg_pools + index;
762
763 sgl = mempool_alloc(sgp->pool, gfp_mask);
764 if (unlikely(!sgl))
765 goto enomem;
766
Jens Axboe45711f12007-10-22 21:19:53 +0200767 sg_init_table(sgl, sgp->size);
Jens Axboea3bec5c2007-10-17 19:33:05 +0200768
Jens Axboea8474ce2007-08-07 09:02:51 +0200769 /*
770 * first loop through, set initial index and return value
771 */
FUJITA Tomonori2a7c59e2007-09-18 12:17:28 +0200772 if (!ret)
Jens Axboea8474ce2007-08-07 09:02:51 +0200773 ret = sgl;
Jens Axboea8474ce2007-08-07 09:02:51 +0200774
775 /*
776 * chain previous sglist, if any. we know the previous
777 * sglist must be the biggest one, or we would not have
778 * ended up doing another loop.
779 */
780 if (prev)
781 sg_chain(prev, SCSI_MAX_SG_SEGMENTS, sgl);
782
783 /*
Jens Axboe45711f12007-10-22 21:19:53 +0200784 * if we have nothing left, mark the last segment as
785 * end-of-list
786 */
787 if (!left)
788 sg_mark_end(sgl, this);
789
790 /*
Jens Axboea8474ce2007-08-07 09:02:51 +0200791 * don't allow subsequent mempool allocs to sleep, it would
792 * violate the mempool principle.
793 */
794 gfp_mask &= ~__GFP_WAIT;
795 gfp_mask |= __GFP_HIGH;
796 prev = sgl;
797 } while (left);
798
799 /*
800 * ->use_sg may get modified after dma mapping has potentially
801 * shrunk the number of segments, so keep a copy of it for free.
802 */
803 cmd->__use_sg = cmd->use_sg;
804 return ret;
805enomem:
806 if (ret) {
807 /*
808 * Free entries chained off ret. Since we were trying to
809 * allocate another sglist, we know that all entries are of
810 * the max size.
811 */
812 sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
813 prev = ret;
814 ret = &ret[SCSI_MAX_SG_SEGMENTS - 1];
815
816 while ((sgl = sg_chain_ptr(ret)) != NULL) {
817 ret = &sgl[SCSI_MAX_SG_SEGMENTS - 1];
818 mempool_free(sgl, sgp->pool);
819 }
820
821 mempool_free(prev, sgp->pool);
822 }
823 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824}
825
FUJITA Tomonorib58d9152006-11-16 19:24:10 +0900826EXPORT_SYMBOL(scsi_alloc_sgtable);
827
Jens Axboe0cde8d92007-10-16 11:12:37 +0200828void scsi_free_sgtable(struct scsi_cmnd *cmd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829{
Jens Axboe0cde8d92007-10-16 11:12:37 +0200830 struct scatterlist *sgl = cmd->request_buffer;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 struct scsi_host_sg_pool *sgp;
832
Jens Axboea8474ce2007-08-07 09:02:51 +0200833 /*
834 * if this is the biggest size sglist, check if we have
835 * chained parts we need to free
836 */
837 if (cmd->__use_sg > SCSI_MAX_SG_SEGMENTS) {
838 unsigned short this, left;
839 struct scatterlist *next;
840 unsigned int index;
841
842 left = cmd->__use_sg - (SCSI_MAX_SG_SEGMENTS - 1);
843 next = sg_chain_ptr(&sgl[SCSI_MAX_SG_SEGMENTS - 1]);
844 while (left && next) {
845 sgl = next;
846 this = left;
847 if (this > SCSI_MAX_SG_SEGMENTS) {
848 this = SCSI_MAX_SG_SEGMENTS - 1;
849 index = SG_MEMPOOL_NR - 1;
850 } else
851 index = scsi_sgtable_index(this);
852
853 left -= this;
854
855 sgp = scsi_sg_pools + index;
856
857 if (left)
858 next = sg_chain_ptr(&sgl[sgp->size - 1]);
859
860 mempool_free(sgl, sgp->pool);
861 }
862
863 /*
864 * Restore original, will be freed below
865 */
866 sgl = cmd->request_buffer;
FUJITA Tomonori2a7c59e2007-09-18 12:17:28 +0200867 sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
868 } else
869 sgp = scsi_sg_pools + scsi_sgtable_index(cmd->__use_sg);
Jens Axboea8474ce2007-08-07 09:02:51 +0200870
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871 mempool_free(sgl, sgp->pool);
872}
873
FUJITA Tomonorib58d9152006-11-16 19:24:10 +0900874EXPORT_SYMBOL(scsi_free_sgtable);
875
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876/*
877 * Function: scsi_release_buffers()
878 *
879 * Purpose: Completion processing for block device I/O requests.
880 *
881 * Arguments: cmd - command that we are bailing.
882 *
883 * Lock status: Assumed that no lock is held upon entry.
884 *
885 * Returns: Nothing
886 *
887 * Notes: In the event that an upper level driver rejects a
888 * command, we must release resources allocated during
889 * the __init_io() function. Primarily this would involve
890 * the scatter-gather table, and potentially any bounce
891 * buffers.
892 */
893static void scsi_release_buffers(struct scsi_cmnd *cmd)
894{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 if (cmd->use_sg)
Jens Axboe0cde8d92007-10-16 11:12:37 +0200896 scsi_free_sgtable(cmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897
898 /*
899 * Zero these out. They now point to freed memory, and it is
900 * dangerous to hang onto the pointers.
901 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902 cmd->request_buffer = NULL;
903 cmd->request_bufflen = 0;
904}
905
906/*
907 * Function: scsi_io_completion()
908 *
909 * Purpose: Completion processing for block device I/O requests.
910 *
911 * Arguments: cmd - command that is finished.
912 *
913 * Lock status: Assumed that no lock is held upon entry.
914 *
915 * Returns: Nothing
916 *
917 * Notes: This function is matched in terms of capabilities to
918 * the function that created the scatter-gather list.
919 * In other words, if there are no bounce buffers
920 * (the normal case for most drivers), we don't need
921 * the logic to deal with cleaning up afterwards.
922 *
923 * We must do one of several things here:
924 *
925 * a) Call scsi_end_request. This will finish off the
926 * specified number of sectors. If we are done, the
927 * command block will be released, and the queue
928 * function will be goosed. If we are not done, then
929 * scsi_end_request will directly goose the queue.
930 *
931 * b) We can just use scsi_requeue_command() here. This would
932 * be used if we just wanted to retry, for example.
933 */
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700934void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935{
936 int result = cmd->result;
Christoph Hellwig631c2282006-07-08 20:42:15 +0200937 int this_count = cmd->request_bufflen;
Jens Axboe165125e2007-07-24 09:28:11 +0200938 struct request_queue *q = cmd->device->request_queue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939 struct request *req = cmd->request;
940 int clear_errors = 1;
941 struct scsi_sense_hdr sshdr;
942 int sense_valid = 0;
943 int sense_deferred = 0;
944
Christoph Hellwig631c2282006-07-08 20:42:15 +0200945 scsi_release_buffers(cmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946
947 if (result) {
948 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
949 if (sense_valid)
950 sense_deferred = scsi_sense_is_deferred(&sshdr);
951 }
Christoph Hellwig631c2282006-07-08 20:42:15 +0200952
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
954 req->errors = result;
955 if (result) {
956 clear_errors = 0;
957 if (sense_valid && req->sense) {
958 /*
959 * SG_IO wants current and deferred errors
960 */
961 int len = 8 + cmd->sense_buffer[7];
962
963 if (len > SCSI_SENSE_BUFFERSIZE)
964 len = SCSI_SENSE_BUFFERSIZE;
965 memcpy(req->sense, cmd->sense_buffer, len);
966 req->sense_len = len;
967 }
Pete Wyckoffb22f6872007-03-13 16:53:28 -0400968 }
969 req->data_len = cmd->resid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 }
971
972 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 * Next deal with any sectors which we were able to correctly
974 * handle.
975 */
James Bottomleyd6b0c532006-07-02 10:06:28 -0500976 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
977 "%d bytes done.\n",
978 req->nr_sectors, good_bytes));
979 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980
James Bottomleyd6b0c532006-07-02 10:06:28 -0500981 if (clear_errors)
982 req->errors = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983
James Bottomleyd6b0c532006-07-02 10:06:28 -0500984 /* A number of bytes were successfully read. If there
985 * are leftovers and there is some kind of error
986 * (result != 0), retry the rest.
987 */
988 if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
989 return;
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700990
991 /* good_bytes = 0, or (inclusive) there were leftovers and
992 * result = 0, so scsi_end_request couldn't retry.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993 */
994 if (sense_valid && !sense_deferred) {
995 switch (sshdr.sense_key) {
996 case UNIT_ATTENTION:
997 if (cmd->device->removable) {
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700998 /* Detected disc change. Set a bit
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 * and quietly refuse further access.
1000 */
1001 cmd->device->changed = 1;
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001002 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 return;
1004 } else {
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001005 /* Must have been a power glitch, or a
1006 * bus reset. Could not have been a
1007 * media change, so we just retry the
1008 * request and see what happens.
1009 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 scsi_requeue_command(q, cmd);
1011 return;
1012 }
1013 break;
1014 case ILLEGAL_REQUEST:
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001015 /* If we had an ILLEGAL REQUEST returned, then
1016 * we may have performed an unsupported
1017 * command. The only thing this should be
1018 * would be a ten byte read where only a six
1019 * byte read was supported. Also, on a system
1020 * where READ CAPACITY failed, we may have
1021 * read past the end of the disk.
1022 */
Jens Axboe26a68012005-11-29 21:03:34 +01001023 if ((cmd->device->use_10_for_rw &&
1024 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025 (cmd->cmnd[0] == READ_10 ||
1026 cmd->cmnd[0] == WRITE_10)) {
1027 cmd->device->use_10_for_rw = 0;
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001028 /* This will cause a retry with a
1029 * 6-byte command.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 */
1031 scsi_requeue_command(q, cmd);
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001032 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 } else {
James Bottomleye91442b2005-09-09 10:44:16 -05001034 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 return;
1036 }
1037 break;
1038 case NOT_READY:
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001039 /* If the device is in the process of becoming
James Bottomleyf3e93f72006-04-25 16:48:30 -05001040 * ready, or has a temporary blockage, retry.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 */
James Bottomleyf3e93f72006-04-25 16:48:30 -05001042 if (sshdr.asc == 0x04) {
1043 switch (sshdr.ascq) {
1044 case 0x01: /* becoming ready */
1045 case 0x04: /* format in progress */
1046 case 0x05: /* rebuild in progress */
1047 case 0x06: /* recalculation in progress */
1048 case 0x07: /* operation in progress */
1049 case 0x08: /* Long write in progress */
1050 case 0x09: /* self test in progress */
1051 scsi_requeue_command(q, cmd);
1052 return;
1053 default:
1054 break;
1055 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 }
James Bottomley311b5812007-09-23 09:08:46 -05001057 if (!(req->cmd_flags & REQ_QUIET))
1058 scsi_cmd_print_sense_hdr(cmd,
1059 "Device not ready",
1060 &sshdr);
1061
James Bottomleye91442b2005-09-09 10:44:16 -05001062 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 return;
1064 case VOLUME_OVERFLOW:
Jens Axboe4aff5e22006-08-10 08:44:47 +02001065 if (!(req->cmd_flags & REQ_QUIET)) {
Jeff Garzik3bf743e2005-10-24 18:04:06 -04001066 scmd_printk(KERN_INFO, cmd,
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001067 "Volume overflow, CDB: ");
Christoph Hellwig631c2282006-07-08 20:42:15 +02001068 __scsi_print_command(cmd->cmnd);
James Bottomley3173d8c2005-09-04 11:32:05 -05001069 scsi_print_sense("", cmd);
1070 }
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001071 /* See SSC3rXX or current. */
1072 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073 return;
1074 default:
1075 break;
1076 }
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001077 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 if (host_byte(result) == DID_RESET) {
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001079 /* Third party bus reset or reset for error recovery
1080 * reasons. Just retry the request and see what
1081 * happens.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082 */
1083 scsi_requeue_command(q, cmd);
1084 return;
1085 }
1086 if (result) {
Jens Axboe4aff5e22006-08-10 08:44:47 +02001087 if (!(req->cmd_flags & REQ_QUIET)) {
Martin K. Petersena4d04a42007-02-27 22:40:27 -05001088 scsi_print_result(cmd);
James Bottomley3173d8c2005-09-04 11:32:05 -05001089 if (driver_byte(result) & DRIVER_SENSE)
1090 scsi_print_sense("", cmd);
1091 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092 }
Luben Tuikov03aba2f2006-06-23 09:39:09 -07001093 scsi_end_request(cmd, 0, this_count, !result);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095
1096/*
1097 * Function: scsi_init_io()
1098 *
1099 * Purpose: SCSI I/O initialize function.
1100 *
1101 * Arguments: cmd - Command descriptor we wish to initialize
1102 *
1103 * Returns: 0 on success
1104 * BLKPREP_DEFER if the failure is retryable
1105 * BLKPREP_KILL if the failure is fatal
1106 */
1107static int scsi_init_io(struct scsi_cmnd *cmd)
1108{
1109 struct request *req = cmd->request;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 int count;
1111
1112 /*
Christoph Hellwig3b003152006-11-04 20:10:55 +01001113 * We used to not use scatter-gather for single segment request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 * but now we do (it makes highmem I/O easier to support without
1115 * kmapping pages)
1116 */
1117 cmd->use_sg = req->nr_phys_segments;
1118
1119 /*
Christoph Hellwig3b003152006-11-04 20:10:55 +01001120 * If sg table allocation fails, requeue request later.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 */
Jens Axboea8474ce2007-08-07 09:02:51 +02001122 cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
1123 if (unlikely(!cmd->request_buffer)) {
Alan Stern7c72ce82005-10-14 11:23:27 -04001124 scsi_unprep_request(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 return BLKPREP_DEFER;
Alan Stern7c72ce82005-10-14 11:23:27 -04001126 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127
Christoph Hellwig3b003152006-11-04 20:10:55 +01001128 req->buffer = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 if (blk_pc_request(req))
1130 cmd->request_bufflen = req->data_len;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001131 else
1132 cmd->request_bufflen = req->nr_sectors << 9;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133
1134 /*
1135 * Next, walk the list, and fill in the addresses and sizes of
1136 * each segment.
1137 */
1138 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 if (likely(count <= cmd->use_sg)) {
1140 cmd->use_sg = count;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001141 return BLKPREP_OK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 }
1143
1144 printk(KERN_ERR "Incorrect number of segments after building list\n");
1145 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
1146 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
1147 req->current_nr_sectors);
1148
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 return BLKPREP_KILL;
1150}
1151
Christoph Hellwig3b003152006-11-04 20:10:55 +01001152static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1153 struct request *req)
1154{
1155 struct scsi_cmnd *cmd;
1156
1157 if (!req->special) {
1158 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1159 if (unlikely(!cmd))
1160 return NULL;
1161 req->special = cmd;
1162 } else {
1163 cmd = req->special;
1164 }
1165
1166 /* pull a tag out of the request if we have one */
1167 cmd->tag = req->tag;
1168 cmd->request = req;
1169
1170 return cmd;
1171}
1172
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001173int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
James Bottomley7b163182005-12-15 20:17:02 -06001174{
Christoph Hellwig3b003152006-11-04 20:10:55 +01001175 struct scsi_cmnd *cmd;
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001176 int ret = scsi_prep_state_check(sdev, req);
1177
1178 if (ret != BLKPREP_OK)
1179 return ret;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001180
1181 cmd = scsi_get_cmd_from_req(sdev, req);
1182 if (unlikely(!cmd))
1183 return BLKPREP_DEFER;
1184
1185 /*
1186 * BLOCK_PC requests may transfer data, in which case they must
1187 * a bio attached to them. Or they might contain a SCSI command
1188 * that does not transfer data, in which case they may optionally
1189 * submit a request without an attached bio.
1190 */
1191 if (req->bio) {
1192 int ret;
1193
1194 BUG_ON(!req->nr_phys_segments);
1195
1196 ret = scsi_init_io(cmd);
1197 if (unlikely(ret))
1198 return ret;
1199 } else {
1200 BUG_ON(req->data_len);
1201 BUG_ON(req->data);
1202
1203 cmd->request_bufflen = 0;
1204 cmd->request_buffer = NULL;
1205 cmd->use_sg = 0;
1206 req->buffer = NULL;
1207 }
James Bottomley7b163182005-12-15 20:17:02 -06001208
Alexey Dobriyan46c43db2006-10-08 15:55:55 +04001209 BUILD_BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd));
James Bottomley7b163182005-12-15 20:17:02 -06001210 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1211 cmd->cmd_len = req->cmd_len;
1212 if (!req->data_len)
1213 cmd->sc_data_direction = DMA_NONE;
1214 else if (rq_data_dir(req) == WRITE)
1215 cmd->sc_data_direction = DMA_TO_DEVICE;
1216 else
1217 cmd->sc_data_direction = DMA_FROM_DEVICE;
1218
1219 cmd->transfersize = req->data_len;
1220 cmd->allowed = req->retries;
1221 cmd->timeout_per_command = req->timeout;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001222 return BLKPREP_OK;
1223}
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001224EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
Christoph Hellwig3b003152006-11-04 20:10:55 +01001225
1226/*
1227 * Setup a REQ_TYPE_FS command. These are simple read/write request
1228 * from filesystems that still need to be translated to SCSI CDBs from
1229 * the ULD.
1230 */
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001231int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
Christoph Hellwig3b003152006-11-04 20:10:55 +01001232{
1233 struct scsi_cmnd *cmd;
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001234 int ret = scsi_prep_state_check(sdev, req);
Christoph Hellwig3b003152006-11-04 20:10:55 +01001235
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001236 if (ret != BLKPREP_OK)
1237 return ret;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001238 /*
1239 * Filesystem requests must transfer data.
1240 */
1241 BUG_ON(!req->nr_phys_segments);
1242
1243 cmd = scsi_get_cmd_from_req(sdev, req);
1244 if (unlikely(!cmd))
1245 return BLKPREP_DEFER;
1246
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001247 return scsi_init_io(cmd);
James Bottomley7b163182005-12-15 20:17:02 -06001248}
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001249EXPORT_SYMBOL(scsi_setup_fs_cmnd);
James Bottomley7b163182005-12-15 20:17:02 -06001250
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001251int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252{
Christoph Hellwig3b003152006-11-04 20:10:55 +01001253 int ret = BLKPREP_OK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254
1255 /*
Christoph Hellwig3b003152006-11-04 20:10:55 +01001256 * If the device is not in running state we will reject some
1257 * or all commands.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
Christoph Hellwig3b003152006-11-04 20:10:55 +01001260 switch (sdev->sdev_state) {
1261 case SDEV_OFFLINE:
1262 /*
1263 * If the device is offline we refuse to process any
1264 * commands. The device must be brought online
1265 * before trying any recovery commands.
1266 */
1267 sdev_printk(KERN_ERR, sdev,
1268 "rejecting I/O to offline device\n");
1269 ret = BLKPREP_KILL;
1270 break;
1271 case SDEV_DEL:
1272 /*
1273 * If the device is fully deleted, we refuse to
1274 * process any commands as well.
1275 */
James Bottomley9ccfc752005-10-02 11:45:08 -05001276 sdev_printk(KERN_ERR, sdev,
1277 "rejecting I/O to dead device\n");
Christoph Hellwig3b003152006-11-04 20:10:55 +01001278 ret = BLKPREP_KILL;
1279 break;
1280 case SDEV_QUIESCE:
1281 case SDEV_BLOCK:
1282 /*
1283 * If the devices is blocked we defer normal commands.
1284 */
1285 if (!(req->cmd_flags & REQ_PREEMPT))
1286 ret = BLKPREP_DEFER;
1287 break;
1288 default:
1289 /*
1290 * For any other not fully online state we only allow
1291 * special commands. In particular any user initiated
1292 * command is not allowed.
1293 */
1294 if (!(req->cmd_flags & REQ_PREEMPT))
1295 ret = BLKPREP_KILL;
1296 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 }
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001299 return ret;
1300}
1301EXPORT_SYMBOL(scsi_prep_state_check);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001303int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1304{
1305 struct scsi_device *sdev = q->queuedata;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306
Christoph Hellwig3b003152006-11-04 20:10:55 +01001307 switch (ret) {
1308 case BLKPREP_KILL:
1309 req->errors = DID_NO_CONNECT << 16;
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001310 /* release the command and kill it */
1311 if (req->special) {
1312 struct scsi_cmnd *cmd = req->special;
1313 scsi_release_buffers(cmd);
1314 scsi_put_command(cmd);
1315 req->special = NULL;
1316 }
Christoph Hellwig3b003152006-11-04 20:10:55 +01001317 break;
1318 case BLKPREP_DEFER:
1319 /*
1320 * If we defer, the elv_next_request() returns NULL, but the
1321 * queue must be restarted, so we plug here if no returning
1322 * command will automatically do that.
1323 */
1324 if (sdev->device_busy == 0)
1325 blk_plug_device(q);
1326 break;
1327 default:
1328 req->cmd_flags |= REQ_DONTPREP;
1329 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330
Christoph Hellwig3b003152006-11-04 20:10:55 +01001331 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332}
James Bottomley7f9a6bc2007-08-04 10:06:25 -05001333EXPORT_SYMBOL(scsi_prep_return);
1334
1335static int scsi_prep_fn(struct request_queue *q, struct request *req)
1336{
1337 struct scsi_device *sdev = q->queuedata;
1338 int ret = BLKPREP_KILL;
1339
1340 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1341 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1342 return scsi_prep_return(q, req, ret);
1343}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344
1345/*
1346 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1347 * return 0.
1348 *
1349 * Called with the queue_lock held.
1350 */
1351static inline int scsi_dev_queue_ready(struct request_queue *q,
1352 struct scsi_device *sdev)
1353{
1354 if (sdev->device_busy >= sdev->queue_depth)
1355 return 0;
1356 if (sdev->device_busy == 0 && sdev->device_blocked) {
1357 /*
1358 * unblock after device_blocked iterates to zero
1359 */
1360 if (--sdev->device_blocked == 0) {
1361 SCSI_LOG_MLQUEUE(3,
James Bottomley9ccfc752005-10-02 11:45:08 -05001362 sdev_printk(KERN_INFO, sdev,
1363 "unblocking device at zero depth\n"));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 } else {
1365 blk_plug_device(q);
1366 return 0;
1367 }
1368 }
1369 if (sdev->device_blocked)
1370 return 0;
1371
1372 return 1;
1373}
1374
1375/*
1376 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1377 * return 0. We must end up running the queue again whenever 0 is
1378 * returned, else IO can hang.
1379 *
1380 * Called with host_lock held.
1381 */
1382static inline int scsi_host_queue_ready(struct request_queue *q,
1383 struct Scsi_Host *shost,
1384 struct scsi_device *sdev)
1385{
James Bottomley939647e2005-09-18 15:05:20 -05001386 if (scsi_host_in_recovery(shost))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 return 0;
1388 if (shost->host_busy == 0 && shost->host_blocked) {
1389 /*
1390 * unblock after host_blocked iterates to zero
1391 */
1392 if (--shost->host_blocked == 0) {
1393 SCSI_LOG_MLQUEUE(3,
1394 printk("scsi%d unblocking host at zero depth\n",
1395 shost->host_no));
1396 } else {
1397 blk_plug_device(q);
1398 return 0;
1399 }
1400 }
1401 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1402 shost->host_blocked || shost->host_self_blocked) {
1403 if (list_empty(&sdev->starved_entry))
1404 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1405 return 0;
1406 }
1407
1408 /* We're OK to process the command, so we can't be starved */
1409 if (!list_empty(&sdev->starved_entry))
1410 list_del_init(&sdev->starved_entry);
1411
1412 return 1;
1413}
1414
1415/*
James Bottomleye91442b2005-09-09 10:44:16 -05001416 * Kill a request for a dead device
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 */
Jens Axboe165125e2007-07-24 09:28:11 +02001418static void scsi_kill_request(struct request *req, struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419{
James Bottomleye91442b2005-09-09 10:44:16 -05001420 struct scsi_cmnd *cmd = req->special;
Tejun Heoe36e0c82006-04-11 17:27:53 +09001421 struct scsi_device *sdev = cmd->device;
1422 struct Scsi_Host *shost = sdev->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423
James Bottomley788ce432005-09-09 13:40:23 -05001424 blkdev_dequeue_request(req);
1425
James Bottomleye91442b2005-09-09 10:44:16 -05001426 if (unlikely(cmd == NULL)) {
1427 printk(KERN_CRIT "impossible request in %s.\n",
1428 __FUNCTION__);
1429 BUG();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430 }
James Bottomleye91442b2005-09-09 10:44:16 -05001431
1432 scsi_init_cmd_errh(cmd);
1433 cmd->result = DID_NO_CONNECT << 16;
1434 atomic_inc(&cmd->device->iorequest_cnt);
Tejun Heoe36e0c82006-04-11 17:27:53 +09001435
1436 /*
1437 * SCSI request completion path will do scsi_device_unbusy(),
1438 * bump busy counts. To bump the counters, we need to dance
1439 * with the locks as normal issue path does.
1440 */
1441 sdev->device_busy++;
1442 spin_unlock(sdev->request_queue->queue_lock);
1443 spin_lock(shost->host_lock);
1444 shost->host_busy++;
1445 spin_unlock(shost->host_lock);
1446 spin_lock(sdev->request_queue->queue_lock);
1447
James Bottomleye91442b2005-09-09 10:44:16 -05001448 __scsi_done(cmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449}
1450
Jens Axboe1aea6432006-01-09 16:03:03 +01001451static void scsi_softirq_done(struct request *rq)
1452{
1453 struct scsi_cmnd *cmd = rq->completion_data;
Brian King8884efa2006-02-24 17:10:04 -06001454 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
Jens Axboe1aea6432006-01-09 16:03:03 +01001455 int disposition;
1456
1457 INIT_LIST_HEAD(&cmd->eh_entry);
1458
1459 disposition = scsi_decide_disposition(cmd);
1460 if (disposition != SUCCESS &&
1461 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1462 sdev_printk(KERN_ERR, cmd->device,
1463 "timing out command, waited %lus\n",
1464 wait_for/HZ);
1465 disposition = SUCCESS;
1466 }
1467
1468 scsi_log_completion(cmd, disposition);
1469
1470 switch (disposition) {
1471 case SUCCESS:
1472 scsi_finish_command(cmd);
1473 break;
1474 case NEEDS_RETRY:
Christoph Hellwig596f4822007-01-02 12:56:00 +01001475 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
Jens Axboe1aea6432006-01-09 16:03:03 +01001476 break;
1477 case ADD_TO_MLQUEUE:
1478 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1479 break;
1480 default:
1481 if (!scsi_eh_scmd_add(cmd, 0))
1482 scsi_finish_command(cmd);
1483 }
1484}
1485
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486/*
1487 * Function: scsi_request_fn()
1488 *
1489 * Purpose: Main strategy routine for SCSI.
1490 *
1491 * Arguments: q - Pointer to actual queue.
1492 *
1493 * Returns: Nothing
1494 *
1495 * Lock status: IO request lock assumed to be held when called.
1496 */
1497static void scsi_request_fn(struct request_queue *q)
1498{
1499 struct scsi_device *sdev = q->queuedata;
1500 struct Scsi_Host *shost;
1501 struct scsi_cmnd *cmd;
1502 struct request *req;
1503
1504 if (!sdev) {
1505 printk("scsi: killing requests for dead queue\n");
James Bottomleye91442b2005-09-09 10:44:16 -05001506 while ((req = elv_next_request(q)) != NULL)
1507 scsi_kill_request(req, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 return;
1509 }
1510
1511 if(!get_device(&sdev->sdev_gendev))
1512 /* We must be tearing the block queue down already */
1513 return;
1514
1515 /*
1516 * To start with, we keep looping until the queue is empty, or until
1517 * the host is no longer able to accept any more requests.
1518 */
1519 shost = sdev->host;
1520 while (!blk_queue_plugged(q)) {
1521 int rtn;
1522 /*
1523 * get next queueable request. We do this early to make sure
1524 * that the request is fully prepared even if we cannot
1525 * accept it.
1526 */
1527 req = elv_next_request(q);
1528 if (!req || !scsi_dev_queue_ready(q, sdev))
1529 break;
1530
1531 if (unlikely(!scsi_device_online(sdev))) {
James Bottomley9ccfc752005-10-02 11:45:08 -05001532 sdev_printk(KERN_ERR, sdev,
1533 "rejecting I/O to offline device\n");
James Bottomleye91442b2005-09-09 10:44:16 -05001534 scsi_kill_request(req, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535 continue;
1536 }
1537
1538
1539 /*
1540 * Remove the request from the request list.
1541 */
1542 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1543 blkdev_dequeue_request(req);
1544 sdev->device_busy++;
1545
1546 spin_unlock(q->queue_lock);
James Bottomleye91442b2005-09-09 10:44:16 -05001547 cmd = req->special;
1548 if (unlikely(cmd == NULL)) {
1549 printk(KERN_CRIT "impossible request in %s.\n"
1550 "please mail a stack trace to "
Jens Axboe4aff5e22006-08-10 08:44:47 +02001551 "linux-scsi@vger.kernel.org\n",
James Bottomleye91442b2005-09-09 10:44:16 -05001552 __FUNCTION__);
Jens Axboe4aff5e22006-08-10 08:44:47 +02001553 blk_dump_rq_flags(req, "foo");
James Bottomleye91442b2005-09-09 10:44:16 -05001554 BUG();
1555 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 spin_lock(shost->host_lock);
1557
1558 if (!scsi_host_queue_ready(q, shost, sdev))
1559 goto not_ready;
1560 if (sdev->single_lun) {
1561 if (scsi_target(sdev)->starget_sdev_user &&
1562 scsi_target(sdev)->starget_sdev_user != sdev)
1563 goto not_ready;
1564 scsi_target(sdev)->starget_sdev_user = sdev;
1565 }
1566 shost->host_busy++;
1567
1568 /*
1569 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1570 * take the lock again.
1571 */
1572 spin_unlock_irq(shost->host_lock);
1573
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 /*
1575 * Finally, initialize any error handling parameters, and set up
1576 * the timers for timeouts.
1577 */
1578 scsi_init_cmd_errh(cmd);
1579
1580 /*
1581 * Dispatch the command to the low-level driver.
1582 */
1583 rtn = scsi_dispatch_cmd(cmd);
1584 spin_lock_irq(q->queue_lock);
1585 if(rtn) {
1586 /* we're refusing the command; because of
1587 * the way locks get dropped, we need to
1588 * check here if plugging is required */
1589 if(sdev->device_busy == 0)
1590 blk_plug_device(q);
1591
1592 break;
1593 }
1594 }
1595
1596 goto out;
1597
1598 not_ready:
1599 spin_unlock_irq(shost->host_lock);
1600
1601 /*
1602 * lock q, handle tag, requeue req, and decrement device_busy. We
1603 * must return with queue_lock held.
1604 *
1605 * Decrementing device_busy without checking it is OK, as all such
1606 * cases (host limits or settings) should run the queue at some
1607 * later time.
1608 */
1609 spin_lock_irq(q->queue_lock);
1610 blk_requeue_request(q, req);
1611 sdev->device_busy--;
1612 if(sdev->device_busy == 0)
1613 blk_plug_device(q);
1614 out:
1615 /* must be careful here...if we trigger the ->remove() function
1616 * we cannot be holding the q lock */
1617 spin_unlock_irq(q->queue_lock);
1618 put_device(&sdev->sdev_gendev);
1619 spin_lock_irq(q->queue_lock);
1620}
1621
1622u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1623{
1624 struct device *host_dev;
1625 u64 bounce_limit = 0xffffffff;
1626
1627 if (shost->unchecked_isa_dma)
1628 return BLK_BOUNCE_ISA;
1629 /*
1630 * Platforms with virtual-DMA translation
1631 * hardware have no practical limit.
1632 */
1633 if (!PCI_DMA_BUS_IS_PHYS)
1634 return BLK_BOUNCE_ANY;
1635
1636 host_dev = scsi_get_device(shost);
1637 if (host_dev && host_dev->dma_mask)
1638 bounce_limit = *host_dev->dma_mask;
1639
1640 return bounce_limit;
1641}
1642EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1643
FUJITA Tomonorib58d9152006-11-16 19:24:10 +09001644struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1645 request_fn_proc *request_fn)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 struct request_queue *q;
1648
FUJITA Tomonorib58d9152006-11-16 19:24:10 +09001649 q = blk_init_queue(request_fn, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 if (!q)
1651 return NULL;
1652
Jens Axboea8474ce2007-08-07 09:02:51 +02001653 /*
1654 * this limit is imposed by hardware restrictions
1655 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001656 blk_queue_max_hw_segments(q, shost->sg_tablesize);
Jens Axboea8474ce2007-08-07 09:02:51 +02001657
1658 /*
1659 * In the future, sg chaining support will be mandatory and this
1660 * ifdef can then go away. Right now we don't have all archs
1661 * converted, so better keep it safe.
1662 */
1663#ifdef ARCH_HAS_SG_CHAIN
FUJITA Tomonori9cb83c72007-10-16 11:24:32 +02001664 if (shost->use_sg_chaining)
1665 blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
1666 else
1667 blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
Jens Axboea8474ce2007-08-07 09:02:51 +02001668#else
1669 blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
1670#endif
1671
Linus Torvalds1da177e2005-04-16 15:20:36 -07001672 blk_queue_max_sectors(q, shost->max_sectors);
1673 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1674 blk_queue_segment_boundary(q, shost->dma_boundary);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676 if (!shost->use_clustering)
1677 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1678 return q;
1679}
FUJITA Tomonorib58d9152006-11-16 19:24:10 +09001680EXPORT_SYMBOL(__scsi_alloc_queue);
1681
1682struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1683{
1684 struct request_queue *q;
1685
1686 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1687 if (!q)
1688 return NULL;
1689
1690 blk_queue_prep_rq(q, scsi_prep_fn);
FUJITA Tomonorib58d9152006-11-16 19:24:10 +09001691 blk_queue_softirq_done(q, scsi_softirq_done);
1692 return q;
1693}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694
1695void scsi_free_queue(struct request_queue *q)
1696{
1697 blk_cleanup_queue(q);
1698}
1699
1700/*
1701 * Function: scsi_block_requests()
1702 *
1703 * Purpose: Utility function used by low-level drivers to prevent further
1704 * commands from being queued to the device.
1705 *
1706 * Arguments: shost - Host in question
1707 *
1708 * Returns: Nothing
1709 *
1710 * Lock status: No locks are assumed held.
1711 *
1712 * Notes: There is no timer nor any other means by which the requests
1713 * get unblocked other than the low-level driver calling
1714 * scsi_unblock_requests().
1715 */
1716void scsi_block_requests(struct Scsi_Host *shost)
1717{
1718 shost->host_self_blocked = 1;
1719}
1720EXPORT_SYMBOL(scsi_block_requests);
1721
1722/*
1723 * Function: scsi_unblock_requests()
1724 *
1725 * Purpose: Utility function used by low-level drivers to allow further
1726 * commands from being queued to the device.
1727 *
1728 * Arguments: shost - Host in question
1729 *
1730 * Returns: Nothing
1731 *
1732 * Lock status: No locks are assumed held.
1733 *
1734 * Notes: There is no timer nor any other means by which the requests
1735 * get unblocked other than the low-level driver calling
1736 * scsi_unblock_requests().
1737 *
1738 * This is done as an API function so that changes to the
1739 * internals of the scsi mid-layer won't require wholesale
1740 * changes to drivers that use this feature.
1741 */
1742void scsi_unblock_requests(struct Scsi_Host *shost)
1743{
1744 shost->host_self_blocked = 0;
1745 scsi_run_host_queues(shost);
1746}
1747EXPORT_SYMBOL(scsi_unblock_requests);
1748
1749int __init scsi_init_queue(void)
1750{
1751 int i;
1752
Mike Christieaa7b5cd2005-11-11 05:31:41 -06001753 scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1754 sizeof(struct scsi_io_context),
Paul Mundt20c2df82007-07-20 10:11:58 +09001755 0, 0, NULL);
Mike Christieaa7b5cd2005-11-11 05:31:41 -06001756 if (!scsi_io_context_cache) {
1757 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1758 return -ENOMEM;
1759 }
1760
Linus Torvalds1da177e2005-04-16 15:20:36 -07001761 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1762 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1763 int size = sgp->size * sizeof(struct scatterlist);
1764
1765 sgp->slab = kmem_cache_create(sgp->name, size, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09001766 SLAB_HWCACHE_ALIGN, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 if (!sgp->slab) {
1768 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1769 sgp->name);
1770 }
1771
Matthew Dobson93d23412006-03-26 01:37:50 -08001772 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1773 sgp->slab);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 if (!sgp->pool) {
1775 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1776 sgp->name);
1777 }
1778 }
1779
1780 return 0;
1781}
1782
1783void scsi_exit_queue(void)
1784{
1785 int i;
1786
Mike Christieaa7b5cd2005-11-11 05:31:41 -06001787 kmem_cache_destroy(scsi_io_context_cache);
1788
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1790 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1791 mempool_destroy(sgp->pool);
1792 kmem_cache_destroy(sgp->slab);
1793 }
1794}
James Bottomley5baba832006-03-18 14:10:35 -06001795
1796/**
1797 * scsi_mode_select - issue a mode select
1798 * @sdev: SCSI device to be queried
1799 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1800 * @sp: Save page bit (0 == don't save, 1 == save)
1801 * @modepage: mode page being requested
1802 * @buffer: request buffer (may not be smaller than eight bytes)
1803 * @len: length of request buffer.
1804 * @timeout: command timeout
1805 * @retries: number of retries before failing
1806 * @data: returns a structure abstracting the mode header data
1807 * @sense: place to put sense data (or NULL if no sense to be collected).
1808 * must be SCSI_SENSE_BUFFERSIZE big.
1809 *
1810 * Returns zero if successful; negative error number or scsi
1811 * status on error
1812 *
1813 */
1814int
1815scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1816 unsigned char *buffer, int len, int timeout, int retries,
1817 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1818{
1819 unsigned char cmd[10];
1820 unsigned char *real_buffer;
1821 int ret;
1822
1823 memset(cmd, 0, sizeof(cmd));
1824 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1825
1826 if (sdev->use_10_for_ms) {
1827 if (len > 65535)
1828 return -EINVAL;
1829 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1830 if (!real_buffer)
1831 return -ENOMEM;
1832 memcpy(real_buffer + 8, buffer, len);
1833 len += 8;
1834 real_buffer[0] = 0;
1835 real_buffer[1] = 0;
1836 real_buffer[2] = data->medium_type;
1837 real_buffer[3] = data->device_specific;
1838 real_buffer[4] = data->longlba ? 0x01 : 0;
1839 real_buffer[5] = 0;
1840 real_buffer[6] = data->block_descriptor_length >> 8;
1841 real_buffer[7] = data->block_descriptor_length;
1842
1843 cmd[0] = MODE_SELECT_10;
1844 cmd[7] = len >> 8;
1845 cmd[8] = len;
1846 } else {
1847 if (len > 255 || data->block_descriptor_length > 255 ||
1848 data->longlba)
1849 return -EINVAL;
1850
1851 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1852 if (!real_buffer)
1853 return -ENOMEM;
1854 memcpy(real_buffer + 4, buffer, len);
1855 len += 4;
1856 real_buffer[0] = 0;
1857 real_buffer[1] = data->medium_type;
1858 real_buffer[2] = data->device_specific;
1859 real_buffer[3] = data->block_descriptor_length;
1860
1861
1862 cmd[0] = MODE_SELECT;
1863 cmd[4] = len;
1864 }
1865
1866 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1867 sshdr, timeout, retries);
1868 kfree(real_buffer);
1869 return ret;
1870}
1871EXPORT_SYMBOL_GPL(scsi_mode_select);
1872
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873/**
James Bottomleyea73a9f2005-08-28 11:33:52 -05001874 * scsi_mode_sense - issue a mode sense, falling back from 10 to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 * six bytes if necessary.
James Bottomley1cf72692005-08-28 11:27:01 -05001876 * @sdev: SCSI device to be queried
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 * @dbd: set if mode sense will allow block descriptors to be returned
1878 * @modepage: mode page being requested
1879 * @buffer: request buffer (may not be smaller than eight bytes)
1880 * @len: length of request buffer.
1881 * @timeout: command timeout
1882 * @retries: number of retries before failing
1883 * @data: returns a structure abstracting the mode header data
James Bottomley1cf72692005-08-28 11:27:01 -05001884 * @sense: place to put sense data (or NULL if no sense to be collected).
1885 * must be SCSI_SENSE_BUFFERSIZE big.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886 *
1887 * Returns zero if unsuccessful, or the header offset (either 4
1888 * or 8 depending on whether a six or ten byte command was
1889 * issued) if successful.
1890 **/
1891int
James Bottomley1cf72692005-08-28 11:27:01 -05001892scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893 unsigned char *buffer, int len, int timeout, int retries,
James Bottomley5baba832006-03-18 14:10:35 -06001894 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1895{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896 unsigned char cmd[12];
1897 int use_10_for_ms;
1898 int header_length;
James Bottomley1cf72692005-08-28 11:27:01 -05001899 int result;
James Bottomleyea73a9f2005-08-28 11:33:52 -05001900 struct scsi_sense_hdr my_sshdr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901
1902 memset(data, 0, sizeof(*data));
1903 memset(&cmd[0], 0, 12);
1904 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1905 cmd[2] = modepage;
1906
James Bottomleyea73a9f2005-08-28 11:33:52 -05001907 /* caller might not be interested in sense, but we need it */
1908 if (!sshdr)
1909 sshdr = &my_sshdr;
1910
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911 retry:
James Bottomley1cf72692005-08-28 11:27:01 -05001912 use_10_for_ms = sdev->use_10_for_ms;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913
1914 if (use_10_for_ms) {
1915 if (len < 8)
1916 len = 8;
1917
1918 cmd[0] = MODE_SENSE_10;
1919 cmd[8] = len;
1920 header_length = 8;
1921 } else {
1922 if (len < 4)
1923 len = 4;
1924
1925 cmd[0] = MODE_SENSE;
1926 cmd[4] = len;
1927 header_length = 4;
1928 }
1929
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930 memset(buffer, 0, len);
1931
James Bottomley1cf72692005-08-28 11:27:01 -05001932 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
James Bottomleyea73a9f2005-08-28 11:33:52 -05001933 sshdr, timeout, retries);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934
1935 /* This code looks awful: what it's doing is making sure an
1936 * ILLEGAL REQUEST sense return identifies the actual command
1937 * byte as the problem. MODE_SENSE commands can return
1938 * ILLEGAL REQUEST if the code page isn't supported */
1939
James Bottomley1cf72692005-08-28 11:27:01 -05001940 if (use_10_for_ms && !scsi_status_is_good(result) &&
1941 (driver_byte(result) & DRIVER_SENSE)) {
James Bottomleyea73a9f2005-08-28 11:33:52 -05001942 if (scsi_sense_valid(sshdr)) {
1943 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1944 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 /*
1946 * Invalid command operation code
1947 */
James Bottomley1cf72692005-08-28 11:27:01 -05001948 sdev->use_10_for_ms = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001949 goto retry;
1950 }
1951 }
1952 }
1953
James Bottomley1cf72692005-08-28 11:27:01 -05001954 if(scsi_status_is_good(result)) {
Al Viro6d73c852006-02-23 02:03:16 +01001955 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1956 (modepage == 6 || modepage == 8))) {
1957 /* Initio breakage? */
1958 header_length = 0;
1959 data->length = 13;
1960 data->medium_type = 0;
1961 data->device_specific = 0;
1962 data->longlba = 0;
1963 data->block_descriptor_length = 0;
1964 } else if(use_10_for_ms) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965 data->length = buffer[0]*256 + buffer[1] + 2;
1966 data->medium_type = buffer[2];
1967 data->device_specific = buffer[3];
1968 data->longlba = buffer[4] & 0x01;
1969 data->block_descriptor_length = buffer[6]*256
1970 + buffer[7];
1971 } else {
1972 data->length = buffer[0] + 1;
1973 data->medium_type = buffer[1];
1974 data->device_specific = buffer[2];
1975 data->block_descriptor_length = buffer[3];
1976 }
Al Viro6d73c852006-02-23 02:03:16 +01001977 data->header_length = header_length;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 }
1979
James Bottomley1cf72692005-08-28 11:27:01 -05001980 return result;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981}
1982EXPORT_SYMBOL(scsi_mode_sense);
1983
1984int
1985scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1986{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987 char cmd[] = {
1988 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1989 };
James Bottomleyea73a9f2005-08-28 11:33:52 -05001990 struct scsi_sense_hdr sshdr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001991 int result;
1992
James Bottomleyea73a9f2005-08-28 11:33:52 -05001993 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, &sshdr,
James Bottomley1cf72692005-08-28 11:27:01 -05001994 timeout, retries);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995
James Bottomley1cf72692005-08-28 11:27:01 -05001996 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997
James Bottomleyea73a9f2005-08-28 11:33:52 -05001998 if ((scsi_sense_valid(&sshdr)) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 ((sshdr.sense_key == UNIT_ATTENTION) ||
2000 (sshdr.sense_key == NOT_READY))) {
2001 sdev->changed = 1;
James Bottomley1cf72692005-08-28 11:27:01 -05002002 result = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002003 }
2004 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005 return result;
2006}
2007EXPORT_SYMBOL(scsi_test_unit_ready);
2008
2009/**
2010 * scsi_device_set_state - Take the given device through the device
2011 * state model.
2012 * @sdev: scsi device to change the state of.
2013 * @state: state to change to.
2014 *
2015 * Returns zero if unsuccessful or an error if the requested
2016 * transition is illegal.
2017 **/
2018int
2019scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2020{
2021 enum scsi_device_state oldstate = sdev->sdev_state;
2022
2023 if (state == oldstate)
2024 return 0;
2025
2026 switch (state) {
2027 case SDEV_CREATED:
2028 /* There are no legal states that come back to
2029 * created. This is the manually initialised start
2030 * state */
2031 goto illegal;
2032
2033 case SDEV_RUNNING:
2034 switch (oldstate) {
2035 case SDEV_CREATED:
2036 case SDEV_OFFLINE:
2037 case SDEV_QUIESCE:
2038 case SDEV_BLOCK:
2039 break;
2040 default:
2041 goto illegal;
2042 }
2043 break;
2044
2045 case SDEV_QUIESCE:
2046 switch (oldstate) {
2047 case SDEV_RUNNING:
2048 case SDEV_OFFLINE:
2049 break;
2050 default:
2051 goto illegal;
2052 }
2053 break;
2054
2055 case SDEV_OFFLINE:
2056 switch (oldstate) {
2057 case SDEV_CREATED:
2058 case SDEV_RUNNING:
2059 case SDEV_QUIESCE:
2060 case SDEV_BLOCK:
2061 break;
2062 default:
2063 goto illegal;
2064 }
2065 break;
2066
2067 case SDEV_BLOCK:
2068 switch (oldstate) {
2069 case SDEV_CREATED:
2070 case SDEV_RUNNING:
2071 break;
2072 default:
2073 goto illegal;
2074 }
2075 break;
2076
2077 case SDEV_CANCEL:
2078 switch (oldstate) {
2079 case SDEV_CREATED:
2080 case SDEV_RUNNING:
Alan Stern9ea72902006-06-23 14:25:34 -04002081 case SDEV_QUIESCE:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002082 case SDEV_OFFLINE:
2083 case SDEV_BLOCK:
2084 break;
2085 default:
2086 goto illegal;
2087 }
2088 break;
2089
2090 case SDEV_DEL:
2091 switch (oldstate) {
Brian King309bd272006-06-27 11:10:43 -05002092 case SDEV_CREATED:
2093 case SDEV_RUNNING:
2094 case SDEV_OFFLINE:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002095 case SDEV_CANCEL:
2096 break;
2097 default:
2098 goto illegal;
2099 }
2100 break;
2101
2102 }
2103 sdev->sdev_state = state;
2104 return 0;
2105
2106 illegal:
2107 SCSI_LOG_ERROR_RECOVERY(1,
James Bottomley9ccfc752005-10-02 11:45:08 -05002108 sdev_printk(KERN_ERR, sdev,
2109 "Illegal state transition %s->%s\n",
2110 scsi_device_state_name(oldstate),
2111 scsi_device_state_name(state))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112 );
2113 return -EINVAL;
2114}
2115EXPORT_SYMBOL(scsi_device_set_state);
2116
2117/**
2118 * scsi_device_quiesce - Block user issued commands.
2119 * @sdev: scsi device to quiesce.
2120 *
2121 * This works by trying to transition to the SDEV_QUIESCE state
2122 * (which must be a legal transition). When the device is in this
2123 * state, only special requests will be accepted, all others will
2124 * be deferred. Since special requests may also be requeued requests,
2125 * a successful return doesn't guarantee the device will be
2126 * totally quiescent.
2127 *
2128 * Must be called with user context, may sleep.
2129 *
2130 * Returns zero if unsuccessful or an error if not.
2131 **/
2132int
2133scsi_device_quiesce(struct scsi_device *sdev)
2134{
2135 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2136 if (err)
2137 return err;
2138
2139 scsi_run_queue(sdev->request_queue);
2140 while (sdev->device_busy) {
2141 msleep_interruptible(200);
2142 scsi_run_queue(sdev->request_queue);
2143 }
2144 return 0;
2145}
2146EXPORT_SYMBOL(scsi_device_quiesce);
2147
2148/**
2149 * scsi_device_resume - Restart user issued commands to a quiesced device.
2150 * @sdev: scsi device to resume.
2151 *
2152 * Moves the device from quiesced back to running and restarts the
2153 * queues.
2154 *
2155 * Must be called with user context, may sleep.
2156 **/
2157void
2158scsi_device_resume(struct scsi_device *sdev)
2159{
2160 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2161 return;
2162 scsi_run_queue(sdev->request_queue);
2163}
2164EXPORT_SYMBOL(scsi_device_resume);
2165
2166static void
2167device_quiesce_fn(struct scsi_device *sdev, void *data)
2168{
2169 scsi_device_quiesce(sdev);
2170}
2171
2172void
2173scsi_target_quiesce(struct scsi_target *starget)
2174{
2175 starget_for_each_device(starget, NULL, device_quiesce_fn);
2176}
2177EXPORT_SYMBOL(scsi_target_quiesce);
2178
2179static void
2180device_resume_fn(struct scsi_device *sdev, void *data)
2181{
2182 scsi_device_resume(sdev);
2183}
2184
2185void
2186scsi_target_resume(struct scsi_target *starget)
2187{
2188 starget_for_each_device(starget, NULL, device_resume_fn);
2189}
2190EXPORT_SYMBOL(scsi_target_resume);
2191
2192/**
2193 * scsi_internal_device_block - internal function to put a device
2194 * temporarily into the SDEV_BLOCK state
2195 * @sdev: device to block
2196 *
2197 * Block request made by scsi lld's to temporarily stop all
2198 * scsi commands on the specified device. Called from interrupt
2199 * or normal process context.
2200 *
2201 * Returns zero if successful or error if not
2202 *
2203 * Notes:
2204 * This routine transitions the device to the SDEV_BLOCK state
2205 * (which must be a legal transition). When the device is in this
2206 * state, all commands are deferred until the scsi lld reenables
2207 * the device with scsi_device_unblock or device_block_tmo fires.
2208 * This routine assumes the host_lock is held on entry.
2209 **/
2210int
2211scsi_internal_device_block(struct scsi_device *sdev)
2212{
Jens Axboe165125e2007-07-24 09:28:11 +02002213 struct request_queue *q = sdev->request_queue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002214 unsigned long flags;
2215 int err = 0;
2216
2217 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2218 if (err)
2219 return err;
2220
2221 /*
2222 * The device has transitioned to SDEV_BLOCK. Stop the
2223 * block layer from calling the midlayer with this device's
2224 * request queue.
2225 */
2226 spin_lock_irqsave(q->queue_lock, flags);
2227 blk_stop_queue(q);
2228 spin_unlock_irqrestore(q->queue_lock, flags);
2229
2230 return 0;
2231}
2232EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2233
2234/**
2235 * scsi_internal_device_unblock - resume a device after a block request
2236 * @sdev: device to resume
2237 *
2238 * Called by scsi lld's or the midlayer to restart the device queue
2239 * for the previously suspended scsi device. Called from interrupt or
2240 * normal process context.
2241 *
2242 * Returns zero if successful or error if not.
2243 *
2244 * Notes:
2245 * This routine transitions the device to the SDEV_RUNNING state
2246 * (which must be a legal transition) allowing the midlayer to
2247 * goose the queue for this device. This routine assumes the
2248 * host_lock is held upon entry.
2249 **/
2250int
2251scsi_internal_device_unblock(struct scsi_device *sdev)
2252{
Jens Axboe165125e2007-07-24 09:28:11 +02002253 struct request_queue *q = sdev->request_queue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002254 int err;
2255 unsigned long flags;
2256
2257 /*
2258 * Try to transition the scsi device to SDEV_RUNNING
2259 * and goose the device queue if successful.
2260 */
2261 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2262 if (err)
2263 return err;
2264
2265 spin_lock_irqsave(q->queue_lock, flags);
2266 blk_start_queue(q);
2267 spin_unlock_irqrestore(q->queue_lock, flags);
2268
2269 return 0;
2270}
2271EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2272
2273static void
2274device_block(struct scsi_device *sdev, void *data)
2275{
2276 scsi_internal_device_block(sdev);
2277}
2278
2279static int
2280target_block(struct device *dev, void *data)
2281{
2282 if (scsi_is_target_device(dev))
2283 starget_for_each_device(to_scsi_target(dev), NULL,
2284 device_block);
2285 return 0;
2286}
2287
2288void
2289scsi_target_block(struct device *dev)
2290{
2291 if (scsi_is_target_device(dev))
2292 starget_for_each_device(to_scsi_target(dev), NULL,
2293 device_block);
2294 else
2295 device_for_each_child(dev, NULL, target_block);
2296}
2297EXPORT_SYMBOL_GPL(scsi_target_block);
2298
2299static void
2300device_unblock(struct scsi_device *sdev, void *data)
2301{
2302 scsi_internal_device_unblock(sdev);
2303}
2304
2305static int
2306target_unblock(struct device *dev, void *data)
2307{
2308 if (scsi_is_target_device(dev))
2309 starget_for_each_device(to_scsi_target(dev), NULL,
2310 device_unblock);
2311 return 0;
2312}
2313
2314void
2315scsi_target_unblock(struct device *dev)
2316{
2317 if (scsi_is_target_device(dev))
2318 starget_for_each_device(to_scsi_target(dev), NULL,
2319 device_unblock);
2320 else
2321 device_for_each_child(dev, NULL, target_unblock);
2322}
2323EXPORT_SYMBOL_GPL(scsi_target_unblock);
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002324
2325/**
2326 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2327 * @sg: scatter-gather list
2328 * @sg_count: number of segments in sg
2329 * @offset: offset in bytes into sg, on return offset into the mapped area
2330 * @len: bytes to map, on return number of bytes mapped
2331 *
2332 * Returns virtual address of the start of the mapped page
2333 */
Jens Axboec6132da2007-10-16 11:08:49 +02002334void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002335 size_t *offset, size_t *len)
2336{
2337 int i;
2338 size_t sg_len = 0, len_complete = 0;
Jens Axboec6132da2007-10-16 11:08:49 +02002339 struct scatterlist *sg;
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002340 struct page *page;
2341
Andrew Morton22cfefb2007-02-05 16:39:03 -08002342 WARN_ON(!irqs_disabled());
2343
Jens Axboec6132da2007-10-16 11:08:49 +02002344 for_each_sg(sgl, sg, sg_count, i) {
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002345 len_complete = sg_len; /* Complete sg-entries */
Jens Axboec6132da2007-10-16 11:08:49 +02002346 sg_len += sg->length;
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002347 if (sg_len > *offset)
2348 break;
2349 }
2350
2351 if (unlikely(i == sg_count)) {
Andrew Morton169e1a22006-04-18 21:09:08 -07002352 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2353 "elements %d\n",
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002354 __FUNCTION__, sg_len, *offset, sg_count);
2355 WARN_ON(1);
2356 return NULL;
2357 }
2358
2359 /* Offset starting from the beginning of first page in this sg-entry */
Jens Axboec6132da2007-10-16 11:08:49 +02002360 *offset = *offset - len_complete + sg->offset;
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002361
2362 /* Assumption: contiguous pages can be accessed as "page + i" */
Jens Axboe45711f12007-10-22 21:19:53 +02002363 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002364 *offset &= ~PAGE_MASK;
2365
2366 /* Bytes in this sg-entry from *offset to the end of the page */
2367 sg_len = PAGE_SIZE - *offset;
2368 if (*len > sg_len)
2369 *len = sg_len;
2370
2371 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2372}
2373EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2374
2375/**
2376 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously
2377 * mapped with scsi_kmap_atomic_sg
2378 * @virt: virtual address to be unmapped
2379 */
2380void scsi_kunmap_atomic_sg(void *virt)
2381{
2382 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2383}
2384EXPORT_SYMBOL(scsi_kunmap_atomic_sg);